Study On The Microbial Mechanisms Of Diesel Degradation In Contaminated Soil By Endophytic Microoganisms From Scirpus Triqueter

As the main water transport channel of Shanghai, the ecological environment of HuangpuRiver shore wetland is being contaminated more and more seriously due to the oil spills. Scirpustriqueter, a dominant species in wetland of Huangpu-Yangtze estuary can be used forphytoremediation.The oil-degrading bacterial strain J4AJ was discovered in vivo of S. triqueter and identifiedas Pseudomonas by sequencing their16S rDNA genes. The proper growth conditions of theoil-degrader J4AJ was33℃, salinity0-1.0%, pH7. The degradation ratio of J4AJ was differingfrom various culture temperatures, the highest value appeared when it was33℃. Thedegradation ratio of J4AJ was different from initial diesel content and surfactant. The lowerinitial diesel content (3000mg/kg) preferred the highest degradation ratio. Furthermore, thedegradation ratio of J4AJ increased by the addition of SLS, APG and Tween-20. However, thedegradation ratio of J4AJ was obviously decreased by the addition of Triton-100.ZF3-1and U-3, two propitious bacterial strains isolated from the root and stem of S.triqueter were identified to be the potent producer of biosurfactant as Bacillus subtilis bysequencing their16S rDNA genes. The minimum surface tension of ZF3-1and U-3were foundas33.14mN/m and30.86mN/m, respectively. Also the two bacterium manifested outstandingcapability at extremes of temperature, pH and at various concentrations of NaCl. The sampleinoculating J4AJ, ZF3-1and U-3displayed the highest removal efficiency (61.19%) in dieseldegradation after7days. The results proved that inoculating strains J4AJ, ZF3-1and U-3weresigificantly conducive to the degradation of diesel, which can be used for the remediation ofoil-contaminated soil and improving the oily ecological environment.In the greenhouse experiment, the degradation of diesel was enhanced by S. triqueter andJ4AJ. It was conceivable inoculating J4AJ enhanced the length and stem biomass of S. triqueter.Besides, dehydrogenase enzyme activity in the rhizospheric soil of planting S. triqueter andinoculating J4AJ was higher than other treatments. The maximum amount of microbial numberwas appeared in the rhizospheric soil of planting S. triqueter and inoculating J4AJ, which hadlower diversity index compared with other treatments. In addition, the microbial communities ofthe rhizospheric soil of planting S. triqueter and inoculating J4AJ were separated from any othertreatments. The synergism of S. triqueter and J4AJ had a beneficial effect on the degradation ofdiesel.